EPIC Ocean Surface PAR: Daily Photosynthetically Available Radiation from Satellite

EPIC satellite observations estimate daily mean photosynthetically available radiation (PAR) at the ice-free ocean surface. The product is generated on an 18.4 km resolution grid and uses a budget approach combining top-of-atmosphere irradiance, atmospheric transmission models, and data from NCEP Reanalysis 2 and MERRA-2. NASA's Atmospheric Science Data Center provides the data, with an algorithm detailed in a 2018 SPIE publication.

Use Cases

• Modeling ocean primary productivity based on daily surface PAR estimates.
• Studying phytoplankton bloom dynamics based on spectral radiation data in the 400-700 nm range.
• Analyzing spatial and temporal patterns in solar energy available for photosynthesis based on the global 18.4 km grid data.
• Integrating surface light fields into biogeochemical or climate models based on the algorithm's use of reanalysis and aerosol data.

Strengths

• Algorithm uses a budget approach that does not require distinguishing clear and cloudy regions within a pixel, avoiding arbitrary cloudiness assumptions.
• Data is compatible with Ocean Biology Processing Group ocean color products on an 18.4 km resolution grid.
• Product incorporates multiple external data sources including wind speed, aerosols, and ozone for atmospheric correction.

Limitations

• Description metadata is limited; actual data quality requires manual inspection after download.
• Column-level documentation is absent; field semantics must be inferred after download.
• The algorithm assumes no cloudiness change during the day for individual observation estimates.

Provenance

Source

National Aeronautics and Space Administration, Atmospheric Science Data Center (ASDC) at NASA Langley Research Center.

Collection Method

Derived from EPIC/DSCOVR satellite observations in spectral bands centered on 443, 551, and 680 nm, combined with modeled atmospheric transmission and external reanalysis data.

Time Range

Example date provided is March 20, 2018; specific temporal coverage is not stated.

Freshness

Last updated 2026-03-13 02:44:26.493308; freshness should be verified.

Geography

Global ice-free ocean surface.